Securing our shared water future amidst climate disruption

[Music]

we all

inherently understand that water is

essential to life

we drink bathe cook and dispose of waste

with it

every day but water is critical to

society

in many ways you may not realize

you need water to make just about

anything

from growing food to making raw

materials like steel

cement paper or plastic to manufacturing

of

all goods including the clothes you’re

wearing

and the screen on which you’re viewing

this talk

for example a cup of coffee requires 140

liters of water

and a smartphone more than 12 000.

water is even needed to generate

electricity

because we use water for almost all

human activity

as society continues to develop our

demand for water

is going to skyrocket with water

being so vital it’s important to ask

where is

all the water on earth we are fortunate

to have a planet with a tremendous

amount of water on it

millions of billions of liters in total

but 97 of this is in the oceans

and you can’t use salt water to drink

or grow food or manufacture goods

of the three percent or so of the water

on earth that is fresh

more than half is locked up in the ice

caps and glaciers

inaccessible to us almost all of the

rest

is under our feet in aquifers so-called

groundwater

now we are heavily reliant on

groundwater

we withdraw it much more rapidly than

it’s naturally replenished

this creates an unsustainable dynamic

that will exhaust this resource before

long

both india and the united states get

more than half of our water for

irrigation from groundwater

how will all that food be grown once

those aquifers run dry

what about surface water lakes and

rivers well

all together those equal only about

0.007 percent

of the water on earth yikes right and

that tiny supply

is becoming even more stressed because

of climate change

precipitation patterns are changing in

many cases making

already dry regions even drier

water crises like the one that happened

in cape town south africa in 2017 or

chennai and 2019 will only become more

common

in the coming years as sea level rises

salt water will start to intrude into

coastal freshwater aquifers

and perhaps most alarmingly the glaciers

and snow whose melt water feeds river

systems

on which billions of peoples rely

are disappearing water crises are

perhaps

most pressing in south asia where india

the largest economy

faces severe shortages and almost

no consensus on what to do about it

water problems threaten to hinder

india’s economic growth

and slow its rise as a regional power

india is not alone many developing

countries face similar challenges

and water often crosses political

boundaries this forces governments to

try and work together

to figure out how much water each side

can use

water sharing has always been difficult

more than four thousand five hundred

years ago in ancient mesopotamia there

were two neighboring city-states of uma

and lagos and they bickered constantly

over a tributary from the euphrates

river

eventually a water sharing agreement was

brokered the

treaty of messily this was not only the

world’s

first water treaty it was actually the

first recorded treaty

of any kind this speaks to the

centrality of water in human

civilization

unfortunately however that peace between

uma and lagash

devolved into conflict just 50 years

later

starting the world’s first but certainly

not its last

water war today in a time of

accelerating economic change and climate

disruption

tensions like these are exacerbated

south asia is reliant on water from two

sources

ice and snow melt from the himalayan

plateau and the annual monsoon rains

both of these sources are destined to

become more unpredictable

and unreliable going forward

moreover there’s already a large

regional dependence on groundwater which

is unsustainable so this cannot be

expanded to provide additional supply

without significant reforms to the way

that south asian nations

use and manage water they and many other

regions around the world

will face deepening economic and social

turbulence

there just won’t be enough water to go

around for sanitation

and growing food and cooling machinery

the outlook feels pretty darn bleak

so what do we do fortunately

developing countries have some powerful

tools available to address water

scarcity and enable

sustainable economic development this

involves

combining two essential elements that

must come together

as an integrated solution the first of

these

is cooperation south asia is both a

model

of international water agreements and an

example of budding water conflict

the indus water treaty between india and

pakistan

and the mekong river commission in south

east south east asia

have both survived decades of interstate

conflict

but contrast that with the case of the

brahmaputra river

which starts in the tibetan area and

flows through china

bhutan india and bangladesh and there is

little agreement over its governance

so first we must build on the successive

agreements like the indus treaty

and strengthen these institutions that

govern transboundary rivers

this isn’t just about india there are

nearly 150

countries around the world that have

international river basins in their

territory

and i should mention many aquifers also

cross political boundaries

creating an impartial incredible forum

to address water disputes will go a long

way

toward reducing these political tensions

so first we must have cooperation but

governments must also bring the second

piece of the story which is

promoting more efficient water use and

this will be through the encouragement

of the development and adoption

of water saving and water recycling

technologies

an obvious step to take is to shift to

more water efficient irrigation methods

less flood irrigation and more drip

irrigation

but there are emerging opportunities for

novel ideas in water

there is an explosion of research

discovery

in new water technologies around the

world some of the most exciting of these

entail taking polluted waste water and

returning it to fit for purpose water

without relying on the slow natural

water cycle to do this

recycling water in this way represents a

complete

reimagining of the water cycle and maybe

the most sustainable impactful path to a

secure water future

now addressing water crises in the

developing world through technology

will require a change in perspective

from those of us in the scientific

community

low-cost highly scalable and distributed

systems will be the key

rather than the high-tech centralized

solutions that we employ so often in the

developed world

let me give you a few examples of some

of these new water technologies with

this different flavor of water

recycling the first example is called

solar steam generation

the idea here is that you take the light

from the sun you convert it to

thermal energy and you concentrate all

of that heat

right at the top of a bath of polluted

water this will dramatically

increase the rate of evaporation leaving

the pollutants behind

you can then just capture the steam

allow it to condense

and you’ve got clean water fit for

almost any use

all driven by a plentiful and carbon

free energy source

the materials for solar steam generation

cost almost nothing

and these devices can be deployed almost

anywhere as long as there’s enough

sunlight

another example comes from the world of

membrane technology membranes are

filters with tiny pores that allow the

water to pass but block the unwanted

substances

they’re a great way to clean water but

there is a pervasive challenge with

membranes

which is that those unwanted substances

will often block the pores

not allowing the water to pass a process

called fouling

here again we can turn to the sun for

help

researchers are developing specialized

coatings that you can apply to membranes

that are activated by

light it creates reactive species that

degrade those fouling substances washing

them off the surface

so your membrane when it gets dirty can

literally clean

itself as long as it’s exposed to light

these are just two examples among a

plethora of promising water technologies

emerging on the horizon it may sound

like i’m

asking you to rely on hope but we don’t

have to rely on hope

we have precedent there are dry places

on earth today

that have combined technology and water

sharing

to produce sustainable water management

in an era of growing regional tensions

and a changing climate

this integration of water cooperation

and technology research and development

as a coupled solution

is a powerful tool a smart investment

for a secure water future for south asia

for the rest of the developing world and

for us all

thank you